Anthers Of Transgenic Plants Research Articles

Expression of Aprotinin in Anther Causes Male Sterility in Tobacco var Petit havana

Expression of many proteinases has been documented during anther development. Although their roles are not completely understood, their inhibition could possibly result in impairment of anther development leading to male sterility. We proposed that such an impairment of anther development can be engineered in plants resulting in male sterile plants that can be used for hybrid seed production. Here, we report that anther-specific expression of Aprotinin gene (serine proteinase inhibitor) in tobacco has resulted in male sterility. Southern analysis and zymogram analysis confirmed the integration and expression of Aprotinin gene in the anthers of the transgenic plants. Transverse sections of anthers of transgenic male sterile plants showed damaged tapetum. The pollen germination in the transgenic plants ranged between 2% and 65% that confirmed the impairment in pollen production leading to male sterility and low seed yield. Thus, inhibition of serine proteinases that are expressed during anther development has resulted in impaired pollen production and male sterility, though the exact role of these proteinases in anther development still has to be elucidated.

A cis regulatory element in the TAPNAC promoter directs tapetal gene expression

The tapetum is a single cell layer surrounding the anther locule and its major function is to provide nutrients for pollen development. The ablation of tapetal cells interferes with pollen production and results in plant male sterility. In spite of the importance of this tissue in the quality and production of pollen grains, studies on promoter gene regulation of tapetal expressed genes are very few and there are no reports on specific cis regulatory sequences that control tapetal gene expression. We have identified a NAC gene, TAPNAC (At1g61110), specifically expressed in the Arabidopsis tapetum via transcriptional profiling. The TAPNAC promoter was studied in detail to identify cis regulatory sequences that confer tapetal specific expression. For this purpose, TAPNAC promoter elements were fused to the β-glucuronidase (GUS) reporter gene, and spatial and temporal GUS expression was monitored. The results showed that TAPNAC promoter-driven GUS expression emulates the expression of TAPNAC mRNA in anthers. A conserved TCGTGT motif was identified in the TAPNAC promoter and other tapetal expressed promoters. The TCGTGT motif enhances GUS expression in anthers of transgenic plants but only in the context of the TAPNAC promoter proximal region.

Overexpression of Zm401, an mRNA-like RNA, has distinct effects on pollen development in maize

We previously identified a 0.7 Kb cDNA fragment of Zm401, a novel pollen-specific gene in maize (Zea mays). However, little information is known about the function of Zm401 in pollen development. The full-length of Zm401 cDNA was amplified by 5′ RACE and 3′ RACE and both sequence analysis and in vitro translation of Zm401 showed that it belonged to an mRNA-like non-coding gene. To analyze its possible biological roles in pollen development, the Zm401 cDNA was overexpressed in transgenic maize under the control of a pollen specific promoter Zm13 or a CaMV 35S promoter. RT-PCR and RNA gel blot analysis indicated that the expression level of Zm401 in leaves and anthers of transgenic plants was much higher than that of non-transformants. Compared with the non-transformed maize, transgenic maize showed distinct phenotypes, such as abnormal tassels and degenerate anthers. The histological observation showed that the development of pollen grains and anthers in transgenic plants were abnormal. These abnormalities include delayed degradation of tapetum, asynchronous fusion of pollen sacs, and aborted pollen grain development. Furthermore, the pollen viability in six transgenic plants ranged from 1.24% to 6.63%. The reduced pollen viability cosegregated with the transgene in a selfed progeny. These results suggest that Zm401 is involved in the regulation of pollen development. This article demonstrated Zm401, as a non-coding RNA, plays an essential role in pollen development.

β-Glucuronidase activity during development of the male gametophyte from transgenic and non-transgenic plants

Beta-glucuronidase (GUS) was histochemically analyzed in anthers and pollen of potato, tobacco and tomato. GUS activity was determined in transgenic plants containing a chimaeric GUS gene and in untransformed plants. In anthers of transgenic plants at premeiotic and meiotic stages of sporogenous development, indigogenic precipitation indicative of GUS activity was consistently manifest in cells of the vascular cylinder, the connectivum and the stomium while no activity was found in the tapetal and sporogenous tissues. At similar stages, anther sections of untransformed plants did not show any indigo blue staining. At later stages of microspore and pollen development, anthers of both transgenic and untransformed plants demonstrated consistently high levels of GUS activity in tapetal and sporogenic cells. In anthers of transgenic plants, GUS was also present in the vascular cylinder, the connectivum and the stomium. These results indicate that in anthers of transgenic potato, tobacco and tomato the chimaeric GUS gene product was localized tissue specifically. They also show that an endogenous GUS gene was expressed in a temporal- and spatial-specific manner in the tapetum and pollen of both transformed and untransformed plants.